Labelling machines are known which substantially comprise a carousel for conveying articles to be labelled, i.e. container filled with a pourable food product, and a pair of labelling groups for applying labels to relative containers advanced by conveyor.
More precisely, each labelling group is provided with a respective web of labels wound to form a reel.
Each labelling group substantially supports the reel rotatably about an axis, winds off the reel along a path, separates a label from the web and applies such a label onto the respective container.
Labelling groups apply, one in alternative with one another, respective plurality of labels onto articles 11 conveyed by carousel.
Labelling groups are furthermore movable between respective operative positions in which they apply labels onto corresponding articles, and respective rest positions.
When labelling machine comprises two labelling groups, a first labelling group is arranged in the relative operative position and applies respective labels onto articles while a second labelling group is idle. Once the reel of the first labelling group has been completely wound off, the first labelling group is arranged in the relative rest position and a second group labelling group is arranged in the operative position.
As second labelling group applies labels onto corresponding articles, a new reel of labels is mounted onto first labelling group.
Finally, once the reel of the second labelling group has been completely wound off, the second labelling group is arranged in the relative rest position and the first labelling group with new reel mounted thereon is arranged in the relative operative position.
In this way, the time losses due to the change of the reel are dramatically reduced and the rate of the labelling machine is, therefore, highly enhanced.
Labelling machine also comprises a vertical cylindrical protective wall which surrounds the conveyor, so as to avoid that operators may be injured by the operation of carousel and labelling group.
In particular, labelling groups are partially arranged within the protective wall when they are arranged in respective operative positions, so as to apply labels onto articles conveyed by conveyor.
Differently, labelling groups are arranged outside the protective wall, when they are arranged in respective rest positions, so that an operator may easily mount a new reel onto such labelling groups.
In order to allow labelling groups to be moved from respective operative to respective rest positions, the protective wall comprises two openings through which labelling groups pass.
When they are required to apply labels at a low rate, labelling machines may comprise only one labelling group, which is movable between respective rest and operative positions.
In the latter case, the protective wall comprises only one opening through which the only one labelling group may pass.
Regardless of the number of labelling groups, there is the risk, when each labelling group is in the relative rest position, that the operator may accidently insert a part of his body, i.e. a hand, through the opening and, therefore, that he/she may be injured by the operation of the labelling machine.
To reduce such a risk, labelling machines are known which comprise two panels each movable between a relative closed position in which it covers a respective opening and a relative open position in which it leaves the respective opening free.
Furthermore, a pair of sensor detects the position of the labelling groups, and a plurality of actuators controlled by respective sensors move respective panels between respective closed and open positions.
Clearly, in case that it comprises only one labelling group, the labelling machine comprises only one panel movable between a closed position in which it covers the only one opening and an open position in which it leaves free the only one opening. In a completely analogous manner, this kind of labelling machine comprises only one sensor for detecting the position of the only one panel.
Regardless of the number of labelling group, a failure in the sensor(s) and/or the actuator(s) causes the panel/one of the panels to remain open when respective labelling group is in the rest position, so generating the risk that the operator could unintentionally insert a hand in the opening and be injured by the moving parts of the labelling machine.
Furthermore, in case he/she unintentionally inserts a hand in the opening when the panel(s) moves/move between respective open to respective closed position(s), the operator is likely to be injured by the moving parts of the labelling machine.
Finally, actuators are costly, so resulting in an increased overall cost of the labelling machine.